Refining hydrocarbon oils



E. C;4 HERTHEL ET AL April 29, 1930.

Patented Apr. 29, 1930 UNITED STATES PATENT OFFICE EUGENE C. HEBTHEL, OF CHICAGO, ILLINOIS, AND HARRY L. PELZER, OF HIGHLAND, A ND JAMES G. STAFFORD, 0F WHITING, INDIANA, ASSIGNORS TO SINCLAIR RE- FINING COMPANY, OF NEW YORK, N. Y., A CORPORATION OF MAINE REFIN'ING HYDROCARBON OILS Application led .Tune 16,

This invention relates to improvements in the manufacture of lubricating oils, and provides an improved method of producing lubricating oils from oils containing lubricat ing oil fractions, such as crude petroleum oils, topped crude oils, and the like. The invention is of special value and application in the manufacture of lubricating oils from certain types of crude oils or crude oil stocks of which the Gulf coast, south Texas, oils and the California oils may be taken as examples. In one aspect, this invention is an improvement upon the operation described in an application of Eugene C. Herthel and Harry L. Pelzer filed June 16, 1928, Serial No. 285,821.

In general, lubricating oils may be defined as oils heavier than gas oil, heavier than about B., and having viscosities upwards of about 50 at 100 F. Saybolt universal.

There is a group of constituents, apparently characteristic of naphthene base crude oils, which are extremely objectionable as components of lubricating oils in particular. These constituents are particularly objectionable in that they render unstable lubricating oils in which they are present. They also impair the quality of lubricating oils containing them in other respects, color for example.`

As yet, this group of objectionable constituents has not been definitely identified. These objectionable constituents are themselves apparently of relatively low boiling point, yet they polymerize quite readily to form a tar or tarry substance. This polymerization is promoted, for example, by the presence of air or steam. With certain types of stocks, additional quantities of these objectionable constituents seem to be formed as long as the oil is maintained at elevated temperature, this effect increasing With teinperature increase.

A number of schemes of procedure have been proposed intended to avoid the objectionable incidents of the presence of this group of objectionable constituents in lubrieating oils, but these proposals have not been entirely satisfactory; in some cases because 1928.` Serial N'o. 285,822.

of operating difiicultiesl and in other cases because of failure to reach the real difficulty. Treatments of the raw stock preceding distillation have been proposed; such treatments are not effective with respect to objectionable constituents formed during distillation. Treatments of the raw stock supplied to and co-incidental with distillation have been proosed; in shell still distillations coke troubles ave been encountered with crude stocks and in pipe still distillation corrosion difliculties have been encountered. In practice, the expedient most generally adopted has been to rerun the lubricating oil distillate fraction or fractions over caustic alkali but this `scheine likewise is knot entirely satisfactory;

additional distillation operations are required, in some cases the lubricating oil distillate fraction must be rerun a second or third time, and rerunningsubjects the lubricating oil to elevated temperatures over further prolonged periods of time. For the most part previous proposals further have been defective in the proper application of the principles of' fractionation to accomplish the desired results.

Hitherto, the manufacture of lubricating oils has also almost uniformly involved refining With sulphuric acid, notwithstandin recognition of several disadvantages of suc acid refining. In many cases this invention makes acid refining operations unnecessary.

The present invention provides an improved method of producing lubricating oils from oils containing lubricating oil fractions .in which a treatment With caustic alkali and a treatment with an adsorbent agent are combined with a fractiohating operation in a particularly advantageous manner, and in a manner particularly advantageous with respect to elimination of constituents of the objectionable group noted above in cases where such objectionable constituents are present.

In carrying out the present invention, a stream of stock containing lubricating oil constituents is fiowed through a heating zone into a vapor separating zone, the stock is heated to a relatively low vaporizing temperature in the heating zone, the vapors sep arated in the vapor separating zone, includ- 5 eating oil constituents escaping from the hot alkaline bath are subjected to a fractionating operation in which higher boiling constituents are condensed, the remaining vapors includin the lubricating oil constituents are taken ottg from this fractlonating operation, a lubricating oil fraction or a series of lubricating oil fractions is condensed therefrom, and the lubricatin oil fraction or fractions as condensed am? while still at a temperature approximating i300-600 F. is contacted with a comminuted solid adsorbent such as fullers earth, advantageously in the presence of a maintained atmosphere of a non-oxidizing, or better a reducing, gaseous medium.

Objectionable decomposition in the heating zone 1s avoided by limiting the time of passage of the oil through the heating zone and by limitin the tem erature to which the oil is heated t erein. n the va or separating zone the vaporization of the ubricat-ing oil constituents is with advantage promoted by the introduction of a distillatlon medium, superheated steam or some other superheated gaseous medium for example. The introduction of steam at this point has certain special e 85 first car advantages noted b ow. The vapor separation ma be carried out co-incidentally with the alkaline treatment; it is advantageous, however, to separate these operations 'ng out the vapor separation and taking o vapors including the lubricating oil constituents therefrom and then subjecting these vapors includin the lubricating oil constituents to the al aline treatment. Where a distillation medium is supplied to the vapor separating operation, it yis with advantage sup lied at a temperature higher than that at w 'ch the oil leaves the heating zone.

By carrying out the heating and vaporizing operations as just described, the heating operation is carried out etlicientl and vaporization of evenl the heavier lu ricating 'oil constituents is effected while subjecting the oil containing these lubricating 011 constituents to high temperatures for but a minimum time. A distillation medium may be passed through the heating zone with the raw stock but it is more advantageously introduced into the vapor separating zone where it is none the less effective in promoting vaporization of the lubricating oil constituents without interfering with the heatin operation. Ob- 'ectionable decomposition ue to local overheating is avoided by maintaining rapid flow through the heating zone, by carr ing out the vapor separation in an externa y unheated zone, and by utilizing a distillation medium.

The hot alkaline treatment is with advantage carried out as described in an application of Eugene C. Herthel and Harry L. Pelzer, filed June 16, 1928, Serial No. 285,820.

ln the hot liquid alkaline oil bath, the lubricating oil constituents are subjected as vapors to intimate contact with caustic alkali. 'llie caustic alkali neutralizes acidic constituents of the oil vapors and, apparently, also acts as a polymerizing agent promoting the polymerization of constituents of the objectionable group noted above. Steam used as a distillation medium in the vapor separation also assists in this polymerization and in soule cases seems to make the caustic alkali more active. In any event, it is necessary, to secure the advantages of the invention, to fractionally condense higher boiling constituents from the vapors including the lubricating oil constituents escaping from the hot alkaline treatment before condensing the lubricating oil product or products. The high boiling constituents separated in this fractionating operation following the hot alkaline treatment and preceding condensation of the lubricatin oil include reaction products of the hot alkaline treatment and the products of polymerization of any objectionable constituents present. Where the vapor separation and the alkaline treatment are carried out co-incidentally, these reaction products where the alkaline treatment is carried out separately from and subsequent to the vapor separation these reaction products and polymerization products may be separated as a separate caustic tar representing but a minor proportion of the total residuum.

The caustic alkali is advantageously supplied to the treating bath as a concentrated aqueous solution; when so supplied the water is evaporated from the bath leaving the alkali in suspension in a tine state of division throughout the bath. It is important that suthcient alkali be supplied to maintain the treating bath alkaline throughout the operation.

Following fractional condensation of high boiling constituents including these reaction products and polymerization products from the vapors including the lubricating oil constituents, the lubricating oil constituents may be condensed as a lubricating oil fraction or as a series of lubricating oil fractions. This separation of the lubricating oil product or in low boiling form or formed in the vapor mixture after leaving the fractionating operation precedino' the first separation of a lubricating oil product.

The lubricating oil fraction or fractions,

as condensed and before any substantial 1 cooling below the temperature range in which the condensation is carried out, is then contacted with a comminuted solid ladsorbent such as fullers earth. This treatment is carried out as a unitary part of the complete operation. Where fullers earth is used, the amount may vary, for example, from 1% to 10% on the weight of the condensate treated, about 8% usually being satisfactory. Amounts of fullers earth in excess of 30% usually make the suspension in the treating bath too thick to handle easily.

his treatmentwith a solid adsorbent is advantageously carried out by maintaining the comminuted solid adsorbent in suspension in a condensate bath to which the lubrieating oil fraction is supplied as condensed, and the vapors supplied to the fractionating operation in which this lubricating oil fraction is condensed may with advantage be passed through this hot bath of condensate containing the comminuted solid adsorbent in suspension on their way to the condensing operation. The treated condensed lubrilfatilig oil fraction is discharged from this The treatment with a solid adsorbent is with advantage carried out as described in an application of James G. Stafford filed June 16 1928, Serial No. 286,073.

zThe treatment with a solid adsorbent is vantageously carried out in the presence of a maintained atmosphere of a non-oxidizing, or better a reducing, gaseous medium. he gaseous media useful for this purpose include hydrogen, carbon dioxide, nitrogen, natural gas and pressure still tail gases.

he comminuted solid adsorbent is. maintained in an active condition by supplying fresh adsorbent to and discharging spent adsorbent from the treating bath as the oper. ation proceeds. The comminuated solid adsorbent may be maintained in suspension in the treating bath by mechanical agitation, or y the introduction of an extraneous gaseous medium, the treating gas for example, or by the introduction of the vapor mixture from which the constituents to be treated are condensed, or by a combination of these means.

The spent adsorbent is with advantage discharged in suspension in the treated condensed lubricating oil fraction discharged from the treatin bath. The suspended solid ie separated from the disadsorbent may charged lubricating oil fraction by filtering the oil while hot, for example atsubstantially the temperature at which it is discharged from the treating bath, or by first cooling the oil and then filtering the cooled oil.

The invention will be further described in connection with the accompanying drawings which illustrate, diagrammatically and conventionally, one form of apparatus for carrying out the invention.

The apparatus illustrated comprises a steam or gas superheater 1, an oil heater 2, a vapor se arating tower 3, a combined treating and ractionating tower 4, a series of fractionating towers 5, 6, 7 and 8, the condenser 9, a series of coolers 10,v 11, 12, 13, 14 and 15, and a series of hot oil filters 40, 41 and 42. Raw stock is supplied through connection 16 by means of a pump 31, fiowed through oil heater 2 and thence into the lower end of vapor separating tower 3, unvaporized residue is discharged through cooler 10, the se arated vapors escape from the upper end o tower 3 to the lower end of treating and fractionating tower 4 through connection 17, vapors escape from the upper end ofl severally discharged through coolers 12, 13, 14 and 15 respectively, the condensates separated in towers 5, 6 and 7 may pass through filters 40, 41 and 42 on the Way, and vapors escaping from the upper end of tower 8 are passed through condenser 9 where they are subjected to final condensation. Steam is supplied to the superheater 1 through connection 18, or other gaseous medium may be supplied through connection 19. The superheater 1 is connected through connection 20 with valved branch connections 43 and 44 for introduction of the superheated gaseous medium therefrom into the lower ends of towers 3 and 4 and through connection 20 and valved connection 61 with valved branch connections 45, 46, 47 and 48 for introduction of the superheated gaseous medium therefrom into the lower ends of towers 5, 6, 7 and 8. Connection 60 is provided to permit the supplying of a different gaseous medium, to the lower ends of towers 5, 6 and 7 than is supplied .from superheater 1; superheated steam may be supplied to the lower ends of towers 3 and 4 from superheater 1 and a treating gas such as natural gas or pressure still tail gases may be supplied to the lower ends of towers 5, 6, 7 and 8 through connection 60, for example. Cooling coils 23, 24, 25, 26, 27 and 28, are provided in the upper ends of the several towers; raw stock to be su plied to the operation, for example, may Ee circulated through these coils in series or in parallel on its way to the oil heater. Cooling coils 33, 34, 35, 36, 37 and 38, are also provided in the upper ends of the several towers; some supplementary reluxing or controlling cooling medium, water for example, ma be circulated through these coils. By provi 'n a pair of cooling coils in the upper end o each tower, as just described, the major part of the heat to be removed from the upperend of each tower can be absorbed in raw stock to be supplied to the operation and exact control can be had by regulation of the rate of circulation or the temperature \medium. The oil heater of the supplementary reuxing or cooling 2 may be of conventional pipe still construction. To avoid local overheating in particular, part of the escaping waste heating gases may be recirculated through the heating tiues in admixture with fresh hot products of combustion from the firebox. The oil heater discharges into the vapor separating tower 3 at a point somewhat above its lower end to afford an opportunity for complete separation of vaporized constituents from unvaporized residual oil. Above this point of introduction, the vapors are subjected to a fractionating operation for the separation of very heavy constituents, tars and the like. The vapor separating tower 3 may be by-passed by means of connection 32, and the vapor separation and the alkaline treating and fractionating operations carried out together in tower 4, but this usually is less advantageous. Vapor connection 17 from the upper end of tower 3 to the lower end of tower 4 terminates in a normally submerged inlet pipe 21 for the introduction of the vapors beneath the normal liquid level in the lower end of tower 4, and connection 22 is provided for the introduction into the vapors owing from connection 17 and pipe 21 of caustic alkali. Vapor connection 29 from the upper end of tower 4 to the lower end of tower 5 also terminates in a normally submerged inlet pipe 49 for the introduction of the vapors beneath the normal liquid level in the lower end of tower 5. The vapor connections 30 and 32 from the upper end of tower 5 to the lower end of tower 6 and from the upper end of tower 6 to the lower end of tower 7, respectively, are similarly arranged terminating in normally submerged inlet pipes 50 and 51. A mechanical agitator 52 is also arranged beneath the normal liquid level in the lower end of each of towers 5, 6 and 7. Means 53 for supplying a commnuted solid adsorbent to the lower end of towers 5, 6 and 7 are also provided. Vapors escaping from the upper end of tower 7 are discharged into tower 8 at a point somewhat above its lower end, the vapors being subjected to a fractionating operation above the point of introduction and the condensate being subjected to a stripping operation for the separation of low boiling constituents below the point of introduction. A hot gaseous medium, superheated steam or other superheated gaseous medium from the superheater 1 or a hot treating gas, for example, from connection is supplie to the lower ends of tower"Y 5,6, 7 and 8 through connections 45, 46, 47 and 48 respectively to control, in conjunction with controlled cooling at the upper ends of these towers, the fractionating operations carried out therein. Superheated steam or other hot gaseous medium is supplied to the lower end of tower 3 through connection 43, beneath the stripping section,

and to the lower end of tower 4 through connection 44 as a distillation medium as well as a control medium, and in the case of steam also as a treating agent. Connections 55, 56 and 57 are provided to permit the by-passing of the submerged inlet pipes 49, 50 and 51 and connections 54, 58 and 59 are provided to permit the lay-passing of the hot oil filters 40, 41 and 42. Tower 3 may be of open bailie construction or of so-called bubble plate construction. Towers 4, 5, 6, 7 and 8 are with advantage of bubble plate or other construction adapted to secure close fractionation. The several towers, particularly towers 3 and 4, and the vapor connections between them, are with advantage lagged or thermally insulated to minimize heat loss.

In carrying out the invention in the apparatus illustrated, he raw stock containing lubricating oil constituents, crude oil or topped crude oil for example, is forced through the oil heater 2 into the lower end of the fractionating tower 3 by means of pump 31. In the oil heater, the oil is heated to a limlted vaporizing temperature,-700 F. for example, in a minimum of time. By using a pipe still to carry out this heating, the time during which the oil is passing through the heating operation is usually less in minutes than is the time in hours where shell stills are used for vaporization. The time of passage throu h the pipe still, for example, may be limite not to exceed 10 or 15 minutes, as com ared to periods upwards of 10 hours in shel stills. In the fractionating tower 3, the lubricating oil constituents are separated or vaporized and separated from the unvaporized residual oil and the latter discharged through cooler 10. To promote this vaporization and separation, superheated steam, at temperatures in the neighborhood of SOO-900 F. for example, or other distillation medium, is supplied from the superheater 1 through connection 43. The operation of tower 3, as well as the operation of the remaining towers 4, 5, 6, 7 and 8, is controlled by regulated cooling at the upper end of the tower and by regulated heating at the lower end of the tower. The vapors containing lubricating oil constituents escaping from the upper end of tower 3 through line 17 are bubbled through a hot liquid oil bath maintained in the lower end of tower 4, being introduced beneath the liquid level thereof through ipe 21. This hot oil bath is maintained alka- 'ne b supplying caustic alkali thereto throng 1 connection 22 and pipe 21. This oil bath is maintained at a temperature sufficiently high to maintain in vapor phase the constituents of the desired lubricating oil products. The vapors escaping from this treat ing bath, includingthe lubricating oil constituents, are subjectedto closely controlled fractionation as they low upwardly through tower 4. The liquid treating bath in the lower end of tower 4 is with advantage maintained of substantially constant volume as the operaalso be used as a distillation medium in towtion proceeds. 4-Any tendency of the bath to ers 3 and 4 or it may be supplied only to towdecrease in volume may be counteracted by ers 5, 6, 7 and 8 and superheated steam or supplying the caustic alkali at a lower temother superheated gaseous medium from the perature, by cooling or increasing the cooling superheater 1 supplied to the lower ends of 7 of the vapors in the upper end of the tower, towers 3 and 4. It is usuallyl most convenient by decreasing the rate of liquid discharge to use the saine gaseous medium as a controlthrough cooler 11, or b decreasing the rate at ling'medium in tower 8 as is used in the imwhich the heating me ium is supplied to the mediatelypreceding towers 5, and 7. As 10 lower end of the tower. Any tendency of the the operation proceeds, treated oil containing 75 bath to increase in volume may be counterthe adsorbent in suspension is discharge acted by supplying the caustic alkali at a from the condensate baths in the lower ends higher temperature, by decreasing the cooling 0f towers 5, 6 and 7 through filters 40, 41 and of the vapors in the upper end of the tower, 4 2 for the removal of the adsorbent and the u by increasing the rate of liquid discharge, or flltered oil then discharged through coolers 80 by increasing the rate at which the heating 12, 13 and 14. i dditional adsorbent 1s supmedium is supplied to the lower end of the piled through means 5.3 as the operation protower. The vapors in the upper end of the ceeds. Vapors escaping uncondensed from tower 4 are cooled sufficiently to condense all tower 8 may be condensed as a naphtha in the tarry constituents or other high boiling con- @Ondenser 9. 85 stituents, including reaction products of the ThefOllOwln example w1ll 1llustrate an alkaline treatment, not suitable as components operation embo ying the invention as carried of the desired lubricatin oil products. In out in apparatus of thety pe illustrated:Gulf the towers 5, 6, 7 and 8, t e vapors escaping coast crude oil is supplie to the oil heater 2 from the upper end of tower 4 are subjected to at a rate of about 10,500 allons per hour and 9o fractional condensation to separate and condlSCbHIged from the oil eater at a temperadense therefrom a series of progressively ture of about 7 50-800 F. An aqueous solulighter and less viscous oil products. For extion of caustic soda, 25 B., is supplied to the ample, a heavy lubricating oil may be conlower end oftower4at arate ofa out 150-250 densed in tower 5, an intermediatelubricating allons per hour. The temperature at the a5 oil in tower 6, a light lubricating oil in toweiottom of tower 3 is maintained at about 720 7 and a gas oil in' tower 8. A bath of conden- F. and at the to at about 700 F.; the temsate is maintained in the lower end of each of perature at the ottoni of tower 4 is maintowers 5, 6 and 7 and acomminuted solid adtained at about 690 F. and at the top at v sorbent such as fullers earth of 1D0-mesh or about 670 F.; the temperature at the bottom 100 finer is supplied to and maintained in suspenof tower 5 is maintained at about 650 F. and sion in these condensate baths. The vapors at the top at about 620 F.; the temperature from the precedin tower are introduced beat the bottom of tower 6 is maintained at neath the normal uid level of each of the about 600 F. and at the top at about 540 bathsin the loweren sof towers 5,6and7 and F.; the temperature at the bottom of tower 105 bubbled therethrough, thus assisting in main- 7 is maintained at about 500 F. and at the taining the adsorbent in suspension in the oil top at about 430 F.; and the temperature at bath at the same time bringing the vapors into the bottom of tower 8 is maintained at about intimate contact with the oil bath. If this ac- 400 F. and at the top at about 330 F. Crude 5 tion is insufficient, in conjunction with the oil to be distilled is circulated through the 110 similar action of any gas introduced through cooling coils in the upper ends of the several connections 45, 46 and 47, to maintain the adtowers and thus preheated. Superheated sorbent in suspension in the oil bath, mecham'- steam' or superheated pressure still tail ases cal agitation is supplied by means of agitators or superheated natural gas, for examp e, at

o 52. The oil baths containing the suspended atemperature in the neighborhood of 900 F. 115

comminuted solid adsorbent in the lower ends 1S Supplied t0 the lOweI ends 0f OWBIS 3 and of towers 5, 6 and 7 are with advantage main.- 4 at rates regulated to maintain the temperatained at temperatures in the general range tures mentioned. Superheated steam at 900 of 500-600 F. while at atmosphere of a non- F. is, for example, supplied to the lower ends oxidizing, or better a reducing, gaseous meof towers 3 and 4 at a combined rate approxi- 120 dium is maintained by supplyingsuchtreating mating 1-3 pounds per gallon of crude oil gas through connections 45, 46 and 47 at a rate supplied to the heater. Pressure still tail sufficient to maintain the baths saturated gases or natural gas, for example, at a temtherewith. Where such a treating gas is su perature in the neighborhood of 7 00-900 F.

30 plied to the lower ends of towers 5, 6 and I7, is supplied to the lower ends of towers 5, 6, 7 125 it is with advantage supplied hot, at temperaand 8 at rates regulated to maintain the temtures in excess of the teni eratures at which peratures mentioned. Fullers earth is supthe vapors from the prece ing tower enter the plied to the lower end of tower 5 at a rate of lower end of each tower, to permit its use as a about 500-1000 pounds per hour, to the lower controlling medium. Such a treating gas may end of tower 6 at a rate of about 1000-1800 130 f arated 'in the ounds per hour and to the lower end of tower i; at a rate of about 800-1500 pounds per hour. Crude oil may thus be separated, for example, into a residuum, about 10% discharged through cooler 10, a caustic bottoms, about 3%, discharged through cooler 11, a heavy lubricating oil, about 10%, discharged through cooler 12, an intermediate lubricating oil, about 20%, discharged through cooler 13, a light lubricating oil, about 13%, discharged through cooler 14, a gas oil, about 35-40%, discharged through cooler 15, and a naphtha discharged throu h condenser 9.

The operation just described makes possible the direct production from Gulf coast crudes, for example, of distilled lubricating oil products which, without further refining treatment, and in particular without acid relining treatment, are of good color and stability. Stable lubricating oils having viscosities as high as 900 at 100 F. or higher and of 11/2 color or better may be so produced. The lubricating oils so produced are of high quality with respect to all the usual re uirements, Conradson carbon test, emulsi ility test, etc.

We claim:

1. In the manufacture of distilled lubri- P cating oils from petroleum stocks, the improvement which comprises flowing a stream of the stock through a heating zone into a vapor separating zone, heating the stock to a vaporizing temperature in the heating zone, separating the vapors from the liquid oil in the separating zone, passing the vapors separated in the vapor separating zone through a hot liquid oil bath maintained alkaline by supplying caustic alkali thereto, subjecting the vapors escaping from the hot alkaline oil bath to a fractionating operation and condensing high boiling constituents therein, taking olf va ors from the fractionating operation an condensing a lubricating oil fraction therefrom, and subjecting the lubricating oil fraction as condensed and while still at elevated temperature to contact with a comminuted solid adsorbent.

2. In the manufacture of distilled lubricating oils from petroleum stocks, the improvement which comprises flowing a stream P of the stock through a heating zone into a vapor separating zone, heating the stock to a vaporizing temperature in the heating zone, separating the vapors from the liquid oil in the separating zone, passing the vapors sepvapor separating zone throu h a hot liquid oil bath maintained alkaline by supplying caustic alkali thereto, subjecting the vapors escaping from the hot alkaline oil bath to a fractionating operation and condensing high boiling constituents therein, taking oil vapors from the fractionating operation and condensing a lubricating oil fraction therefrom, and subjecting the lubricating oil fraction as condensed and while still at a temperature approximating 500'000 F. to contact with a comminuted solid adsorbent.

3, In the manufacture of distilled lubricating oils from petroleum stocks, the improvement which comprises flowing a stream of the stock through a heating zone into a vapor separating zone, heating the stock to a vaporizing temperature in the heating zone, separating the vapors from the liquid oil in the separating zone, passing the vapors separated in the va or separating zone through a hot liquid oil ath maintained alkaline by supplying caustic alkali thereto, subjecting the vapors escaping from the hot alkaline oil bath to a fractionating operation and condensing high boiling constituents therein, taking off vapors from the fractionating operation and condensing a lubricating oil fraction therefrom, and subjecting the lubricating oil fraction as condensed and while still at elevated temperature to contact with a comminuted solid adsorbent in the presence of a maintained atmosphere of a non-oxidizing gas.

4. In the manufacture of distilled lubricating oils from petroleum stocks, the imrovement which comprises flowing a stream of the stock through a heating zone into a vapor separating zone, heating the stock to a vaporizing temperature in the heating zone, separating the vapors from the liquid oil in the separating zone, passing the vapors separated in thevapor separating onle subjecting the vapors escaping from the hot alkaline oil bath to a and condensing high therein, taking 0E va tionating operation an condensin a lubricating oil fraction therefrom, an subjecting the lubricating oil fraction as condense and while still at elevated tem erature to contact with a comminuted soli adsorbent in the resence of a maintained atmosphere of a re ucing gas.

5. In the manufacture of distilled lubri cating oils from petroleum stocks, the imrovement which comprises flowing a stream of the stock through a heating zone into a vapor separating zone, heating the stock to a vaporizing temperature in the heating zone, introducing superheated steam into the vapor separating zone, separating the vapors from the liquid oil in the separating zone, passing the vapors separated in vthevapor separating zone through a hot liquid oil bath maintained alkaline by supplying caustic alkali thereto, subjecting the vapors escaping from the hot alkaline oil bath to a fractienating operation and condensing high boiling constituents therein, taking olf va ors from the fractionating operation an condensing a lubricating oil fraction therefrom, and subject.-

boiling constituents ors from the fracing the lubricating oil fraction as condensed and While still at elevated temperature to Contact with a comminuted solid adsorbent in the presence of a maintained atmosphere of a non-oxidizing gas.

In Witness whereof, We have subscribed our names.

EUGENE C. HERTHEL. HARRY L. PELZER. JAMES G. STAFFORD 

